K'tan Baby Carrier Help?

I bought an original K'tan baby carrier off a local buy and sell page and it didn't come with the sash/carrying bag! I know it can be worn without the sash but part of the reason I like this carrier was the added support of the sash, and having it's own little bag is a plus! I was thinking I could just get some cute fabric and sew a sash of my own but I need to know the dimensions of the bag part, the website says it's the same no matter what size your main wrap part is.

So if anyone has a K'tan and wouldn't mind measuring the just the bag when it's laid flat, that would be great! Thanks! 😊